A constant concern of parents of a sleeping infant, generally less than one year old, is the onset of sudden infant death syndrome (SIDS). Parents usually inspect the breathing patterns of their infant several times during a nighttime period to determine whether there are signs of the onset of SIDS.
It would be desirable to provide a reliable and inexpensive detector for infant apnea, which is one of the most recognizable signs of SIDS. An infant who has ceased to breathe can be revived only if a parent, who has been trained to provide first aid care, is immediately alerted to such a life threatening condition.
Some adults are also prone to sleep apnea due to various medical causes. It would be desirable to provide a reliable and ergonomic detector for monitoring sleep apnea and for stimulating the subject to awake when sleep apnea occurs.
Three types of prior art apnea detectors are known:                1) An apnea detector such as disclosed in U.S. Pat. No. 5,271,412, WO 2005/074379, U.S. Pat. No. 4,146,885 and U.S. Pat. No. 5,684,460 is placed underneath the mattress of the infant, and a parent is immediately alerted when apnea is detected. It is needless to say that this type of detector is unable to detect apnea when the infant is not sleeping, such as when playing, or when not sleeping on his mattress. This type of detector is also relatively expensive to manufacture. Another disadvantage of this type of apnea detector is that the mattress is interposed between the infant and the detector that senses the breathing pattern of the infant. The received signal is therefore attenuated by the mattress material, and its transmission is also delayed due to the gradual relaxation of the spongy mattress material, causing a life threatening delay during an apnea event.        
2) One type of apnea detector, such as disclosed in U.S. Pat. No. 5,454,376 or U.S. Pat. No. 5,241,300, involves a wearing apparel having an elastic belt that extends about the chest or abdomen of the infant. A strain gauge is secured to the belt and detects breathing movement through the expansion and contraction of the chest wall. Such a detector is uncomfortable or even dangerous to the wearer, particularly during the nighttime hours, due to the pressure exerted by the elastic belt, and therefore cannot be used during an entire 24-hour period. Apnea cannot be detected when the wearing apparel is being laundered. Additional disadvantages of this type of detector are that the detector is not suitable for different sized infants and that it is not capable for detecting moisture in a diaper.
U.S. Pat. Nos. 5,295,490, 4,696,307, 4,989,612, 5,107,855, and 5,400,012 disclose a variation of this type of apnea detector in which belt means encircling a portion of the body of a patient expands and contracts in response to respiration of the patient. This belt means poses a risk of entanglement and suffocation to the monitored infant.
3) Another type of apnea detector, such as disclosed in GB 2261290, U.S. Pat. No. 3,782,368, U.S. Pat. No. 5,684,460, U.S. Pat. No. 6,267,730 and WO 2005/011491, comprises a piezoelectric element for detecting deflections caused by respiratory and heart functions. A piezoelectric element is relatively expensive, and therefore is not disposable. Also, a piezoelectric element is fragile, and may be easily broken by the infant or by his parents, therefore constituting an unreliable detector.
Other apnea detectors are disclosed in WO 02/34133, JP 9,187,431, U.S. Pat. Nos. 5,993,397 and 6,267,730.
U.S. Pat. Nos. 5,838,240 and 6,677,859 disclose the use of a capacitive sensor for detecting moisture, such as in a diaper. A capacitive sensor has not been used heretofore to detect sleep apnea.
It is an object of the present invention to provide a reliable and inexpensive detector for infant apnea.
It is an additional object of the present invention to provide an infant apnea detector and system, which are operable throughout a 24-hour period, even when the infant is awake and not in a prone position.
It is an additional object of the present invention to provide an infant apnea sensor that is embedded within a diaper.
It is an additional object of the present invention to provide an infant apnea sensor that is disposable.
It is an additional object of the present invention to provide an infant apnea detector that is comfortable and safe to the infant.
It is an additional object of the present invention to provide an infant apnea detector that is difficult to be removed by the infant from the diaper to which it is attached.
It is an additional object of the present invention to provide an infant apnea detector and system that are also capable of detecting wetness and other infant related parameters of interest.
It is yet an additional object of the present invention to provide an infant apnea detector system that can instantly alert a parent upon detection of apnea.
It is yet an additional object of the present invention to provide an infant apnea detector system that does not expose the infant to close-proximity radio frequency (RF) radiation.
It is yet an additional object of the present invention to provide an infant apnea detector and sensor that are not in direct contact with the body of the infant.
Other objects and advantages of the invention will become apparent as the description proceeds.